Surgeon&#39;s plaster-knife



SURGEONS PLASTER KNIFE.

APPLICATION FILED JULY 2, 1919.

1,336,376, Patented Apr. 6, 1920;

WITNESSES I INVENTOR I By M w ATTORNEYS TINITED STATES PATENT OFFICE.

HERMAN B. PHILIPS, OF NEW YORK, N. Y.

sunenou s PLASTER-KNIFE.

i Application filed July 2,

To all whom 2'25 may concern.-

Be' it known that I, HERMAN B. PHILIPS, a citizen of the United States, and a resident of the city of New York, borough of Manhattan, in the county and State of New York, have invented a new and Improved Surgeons Plaster-Knife, of which the following is a full, clear, and exact description.

This invention relates to surgical instruments and has particular reference to means for removing a plaster cast from a limb after it has been set and healed.

Among the objects of the invention is to avoid the usual difficulty in cutting or slitting the cast without danger of cutting the patient. As the operation is ordinarily effected a single pointed knife is employed and in the use of a knife under considerable force which is required to split or out the cast the knife point is disposed to become jammed or locked in the partially formed slit and also at times to pass entirely through the cast and so endanger the flesh within the cast. V

Another object of the invention is to provide a device including in addition to one or more blades, a member acting as a breaker or reducer of the structure of the cast adjacent to the slit or cleavage formed by the cutting device.

Another object of the invention isto provide a device including a holder with which one or more blades are designed to be detachably connected, the means for connecting them including a member adapted to embrace the blades and holder and serving also as a head against which the operator may direct either a blow or pressure to augment the cutting or digging action of the blade points.

With the foregoing and other objects in view'the invention consistsin the arrangement and combination of parts hereinafter described and claimed, and while the invention is not restricted to the exact details of construction disclosed or suggested herein, still for the purpose of illustrating a practical embodiment thereof reference is bad to the accompanying drawings, in which like reference characters designate the same parts in the several views, and in which Figure 1 is a plan view of my improvement.

Fig. 2 is a side elevation of the same.

Specification of Letters Patent.

Patented Apr. 6, 1920.

Serial No. 308,104.

Fig. 3 is a vertical transverse section on the line 33 of Fig. 2; and

Fig. A is a horizontal section on the line -i l of Fig. 2.

Referring now more specifically to the construction I show a holder 10 comprising a shank 11 at one end and having attached a handle 12 at its other end, the handle being directed upward at an angle to the shank.

In my experience with this instrument I have found that two blades are most advantageously employed in connection with the holder shank, said blades being indicated at 13 and adapted to be clamped to the sides of the shank by any uitable means providing for the easy removal or interchange of the blades with respect to the shank and to each other.

Each of the blades is made of a substantial piece of steel, or its equivalent, having a rectangular shank portion and having at its cutting end a sharp point 14: and a sharp cutting edge 15 leading to the point. In the formation of the cutting edge the metal is beveledoff preferably 011 one side only as at 16. The means for connecting the blades to the holder shank provides that the blades except for the beveling of the edges shall be preferably substantially parallel as indicated in Fig. 3.

The immediate means for securing the blades to the holder shank prevent the swinging of the blades in their own planes consisting preferably of a plurality of pins 17 and corresponding holes or sockets. The pins obviously may be carried either by the blades or by the holder shank, and when carried by the shank will project into or through correspondingly arranged holes 18 formed in the blades. By this means the pins 17 pass entirely through the shank being fitted in holes 19 therein permanently and by making the pins long enough to project from both sides of the shank 11 the blades 13 obviously may be applied directly thereto against the opposite sides of the shank so as to bring the bevels 16 of the blades either on the inside or on the outside according to the conditions of the operation or the preference of the operator. Furthermore while the pins might be carried permanently by the blades and project into holes formed in the shank, such arrangement embraces a blade. These parts are formed so as to have a snug but sliding fit. The blades being fixed to the shank by the p1ns and holes so as to prevent them from movement in any direction except laterally from the shank they constitute means to prevent movement of the head along the shank or blades in any direction except upward. This upward movement is resisted by gravity and frictional engagement between the head and the blades. It follows, therefore, that with the head held in place as indicated the jaws 21 will prevent lateral movement of the blades, thereby for practical purposes the means shown makes an effective connection between the blades and the shank. The removal of the head, however, upward along the blades sets the blades free for removal or interchange that may be required if it is desired to change the positions of the bevels or cutting edges with respect to each other as for bringing the points close to or remote from each other or for putting in sharp blades after one pair have become dull.

Another important feature of the improvement is the breaker consisting of a lug or projection 23 formed preferably integral with the lower edge of the shank between the blades and the handle. The point of the breaker is rounded in the direction of movement of the instrument and lies in a plane preferably midway between the planes of the blades. The breaker projection may be of any suitable length with respect to the points of the blades but preferably as shown somewhat shorter so that if the instrument is drawn along the cast the points of the blades are'operative for slitting'or cutting a groove in the cast without interference or contact by the breaker while the shank is held substantially parallel to the cast. After the slitting operation, however, has been begun and the two blade points have scored the cast sufiiciently, the rounded point of the breaker is brought into action as a result of the entrance of the points into the cast or because of the downward tilting of the handle, or both, and so the breakerrides or scrapes along the central portion of the cast between the two cuts or scores formed by the blade points. The purpose of this action is to serve to break, crumble, or otherwise reduce the portion of the cast between the slits so as to render removal of such portion from the main portion much easier than in the ordinary practice. Another purpose of this breaker is to serve as a guard tending to prevent the passage of the blade points entirely through the cast prematurely so as to endanger the patient.

With reference to Fig. 2 and the two dotted lines a and 1) formed thereon it will be noted that during the main cutting action the line a may represent the surface of the cast and the position of the instrument is-indicated with the shank substantially parallel to the cast so as to secure the greatest efliciencv for the points of the blades. At this time there is no likelihood of injury to the patient due'to the passage of the points through the cast. As the cutting operation proceeds the instrument may be tilted so as to bring it at an inclination to the cast as would correspond to the dotted line b. The inclination of the handle 12 with respect to the shank 11 is sufficient to afford even a greater tilting of the instrument so as to increase the pressure of the breaker on the work as above set forth. The character of the disk 20 of the blade keeper head 19 is such that the left hand of the operator may be applied thereto either by pressure or a blow for the purpose of facilitating the cleavage of the cast.

In the use of this instrument for the trimming of an edge of a cast after it has been formed, it is preferable to use one only of the blades, the guard or breaker at such time being employed as a guide. i

I claim:

1. In a plaster knife, the combination of a holder comprising a rigid shank'and a rigid handle extending rearward therefrom, a cutting blade, pin and hole connections between the blade and the shank serving to prevent movement of the blade with respect to the shank except laterally, and means embracing the bladejand the shank to prevent movement of the blade laterally from the shank.

25111 a plaster knife of the character set forth in claim 1 Whose blade holding means comprises a pair of parallel jaws having vertical slidable engagement with said blade and shank on the opposite faces thereof, and a hand engaging member carrying said aws. V j V 3. In a surgeons plaster knife, the combination of a holder, a plurality of sharp pointed parallel blades cooperating therewith, the points being arranged at the ends of beveled cutting edges, and means to detachably and interchangeably secure the blades to the holder, whereby said blades may be locked to the holder so as to position the points close to or remote from each other. 7 r

4. In a surgeons plaster knife, the combination of a holder comprising a shank, a handle arranged at an oblique angle to the shank and rigid therewith, a pair of parallel blades cooperating with the holder and adapted for simultaneous cutting action, and means to removably and interchangeably secure the blades to the shank portion of the holder.

5. In a surgeons plaster knife, the combination of a holder comprising a shank, a handle arranged at an angle to the shank, cutting means carried by the shank portion of the holder, and a plaster breaker carried by the holder adjacent to the angle between the shank and the handle.

6. In a surgeons plaster knife, the combination of a holder comprising a shank and a handle arranged. at an oblique angle to each other, a round pointed rigid plaster breaker carried by and projecting downward from the holder between the end of the shank and the handle, and cutting means secured to the end portion of the shank and cooperating with said breaker.

7. In a plaster knife of the character set forth, the combination of a holder comprising a rigid shank and a rigid handle extending rearward therefrom, a pair of sharp pointed blades, pin and hole connections between the blades and the shank serving to prevent movement of the blades with respect to the shank except laterally, and means embracing the blades and shank to prerent movement of the blades laterally from the shank.

8. In a surgeons plaster knife, the combination of a holder, a rigid projection eX- tending downward from the holder and serving as a guide and plaster breaker, sharp pointed cutting means cooperating with the holder and operatively related to the projection aforesaid, and quick detachable means for securing the cutting means to the holder.

9. In a. surgeons plaster knife, the combination of a holder, cutting means cooperating therewith and a keeper for the cutting means comprising a disk for the application of the operators hand and comprising a pair of jaws embracing the cutting means and holder and preventing all relative movement between the cutting means and the holder.

HERMAN B. PHILIPS. 

